<h2>DESCRIPTION</h2>


<b>i.cca</b> is an image processing program that takes any number of
(raster) band files and a signature file, and outputs the same number of
raster band files transformed to provide maximum separability of the
categories indicated by the signatures.  This implementation of the
canonical components transformation is based on the algorithm contained in
the <a href="http://dbwww.essc.psu.edu/lasdoc/user/canal.html">LAS image
processing system</a>. CCA is also known as "Canonical components
transformation".

<p>
Typically the user will use the 
<em><a href="g.gui.iclass.html">g.gui.iclass</a></em>
program to collect a set of signatures and then pass those
signatures along with the raster band files to
<em>i.cca</em>.  The raster band file names are specified
on the command line by giving the group and subgroup that
were used to collect the signatures.

<p>
The output raster map names are built by appending a ".1",
".2", etc. to the output raster map name specified on the
command line.

<h3>Parameters:</h3>

<dl>

<dt><b>group=</b><em>name</em> 

<dd>Name of the <a href="i.group.html">imagery</a> group
to which the raster band files used belong.

<dt><b>subgroup=</b><em>name</em> 

<dd>Name of the <a href="i.group.html">imagery</a>
subgroup to which the raster band files used
belong.

<dt><b>signature=</b><em>name</em> 

<dd>Name of an ASCII file containing spectral signatures.

<dt><b>output=</b><em>name</em> 

<dd>Output raster map prefix name.  The output raster map
layer names are built by appending a ".1", ".2", etc. onto
the <em>output</em> name specified by the user.

</dl>

<h2>NOTES</h2>

<em>i.cca</em> respects the current geographic region definition
and the current mask setting while performing the transformation.

<h2>SEE ALSO</h2>

<em>
<a href="g.gui.iclass.html">g.gui.iclass</a>,
<a href="i.gensig.html">i.gensig</a>,
<a href="i.cluster.html">i.cluster</a>,
<a href="i.pca.html">i.pca</a>,
<a href="r.covar.html">r.covar</a>,
<a href="r.mapcalc.html">r.mapcalc</a>
</em>

<h2>REFERENCES</h2>

Schowengerdt, Robert A.  <b>Techniques for Image Processing and
Classification in Remote Sensing</b>,  Academic Press, 1983.

<h2>AUTHORS</h2>

David Satnik, GIS Laboratory, 
Central Washington University
<br>
Ali R. Vali, 
University of Texas
<br>
Band reference support: Maris Nartiss,
University of Latvia

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